Flexible polyurethane foams are well recognized articles of commerce. Flexible foams may be characterized by the process used in production thereof, either molded or free-rise. Free-rise foams are often made in a continuous slabstock process. Molded foams are typically manufactured within an enclosed chamber having the shape of the desired finished article. Flexible foams are widely employed in furniture, mattresses, automotive and numerous other applications. However, it is inherent in these foam types that most cell windows remain fully or partially intact at the time of production, thus necessitating a crushing process to enhance the air flow and to achieve the cushioning and property requirements of the end-use application. For very reactive systems, such as those encountered in molded seating where the reaction and the mold is maintained at elevated temperatures, the foams may exhibit a predominantly closed cell structure that requires immediate hot crushing to avoid shrinkage or warpage of the part.
Foam crushing requires a separate processing step, thereby increasing the cost and time of production. Furthermore, excessively high crushing forces can result in non-useable foam in the intended application if it is not possible to sufficiently open the foam or if the crushing process permanently distorts the part or tears the foam.
Furthermore, some polyurethane foams may have reduced fire retardant properties. In the case of flexible polyurethane foams, the reduced fire retardant properties may be enhanced by the open-cell nature of the foam and the large surface area per unit weight of foam. Therefore, there is a need for a polyurethane foam which does not require a crushing step while at the same time maintains desirable physical properties of the foam and has fire retardant properties.